An exercise machine having a motion converting mechanism that is relevant to the present invention is illustrated in U.S. Pat. No. 4,902,009 issued in the name of Arthur Jones on Feb. 20, 1990. According to this patent, a link is connected to the lower end of one side of an inclined pivot arm and to an ear on the lower portion of an upstanding arm assembly. The arm assembly carries a pair of toggle operated locking pins which can be selectively engaged in angularly arranged upper and lower series of holes in a sprocket wheel. The sprocket wheel is connected to a chain that extends up over a sheave near the top of the machine, and then down to a counterweight assembly. The pins are jointly operated by a toggle arm having its center pivoted to the outer end of a transverse shaft that supports and is rotated by, the side member of a movement frame that is forced backward by the user. The sprocket wheel and the upstanding arm assembly are mounted on this shaft for rotation relative thereto, and the pins cause the sprocket to rotate in response to pivotal movement of the inclined arm and the upstanding arm assembly. A gauge is located in the link so as to provide output signals representative of strain to a computer that is programmed to compute static strength of the user of the machine at the various angles to which the upstanding arm assembly is connected to the sprocket wheel by the toggle arm and pins.
This motion converting mechanism is believed to be entirely too complex, and therefore expensive to manufacture and to maintain. The toggle arm is on the outside of the machine, and pivots with the movement arms as the user pivots the arm backward and forward during each exercise cycle. The toggle arm thus provides a safety hazard to anyone standing near the machine, particularly if the counterweight chain should become severed when the user has tilted the frame member to its rearmost position. This safety hazard is further highlighted by the fact that the toggle arm has an outwardly inclined handle bar at its upper end which could cause very severe injury to someone as the massive counterweight accelerates downward.
The general object of the present invention is to provide a new and improved motion converting mechanism for an exercise machine that is simplified and thus more economical to make and maintain.
Another object of the present invention is to provide a new and improved motion converting mechanism of the type described that is safe and reliable in operation.
Still another object of the present invention is to provide a motion converting mechanism of the type described that includes new and improved means to allow static and dynamic strength measurements to be made during exercise.